I have been coached to believe stopping power rules the day, the reason being if you have a big heavy animal with teeth, tusks, claws or hooves coming at you fast, even if you kill it the animals momentum could carry it into you and a big dead critter can still mess you up if it hits you hard. So the more lead you can throw out with some serious punch behind it the better.

The actual kinetic energy of the round is going to make almost zero difference as far as stopping the animal's momentum. Bigger, more powerful rounds are going to help kill or disable the animal faster, but they aren't going to knock it back or slow its momentum in any measurable way.